EP1066801A1 - Method and device for the manufacture of medical in particular dental prosthesis - Google Patents

Abstract

The method involves machining a workpiece from which a fitting body is to be produced using a material removing tool, whereby the tool and workpiece (1) describe a relative motion along a path and the actual loading on the tool is derived to regulate the speed of the relative motion. The anticipated load on the tool along the path is computed and used to control the relative speed.

Description

The invention relates to a method for creating medical, in particular dental fitting bodies, in which a workpiece from which the fitting body is created is machined with a tool.

Such a method is known for example from EP-A-0 182 098 known. A workpiece made of dental ceramic Material is arranged on a holder, which is at the machining process. Here is the Workpiece optionally from a cutting disc or one edited finger-shaped grinding pin on a Tool carriers are attached. The altitude of the Tool carrier is controlled according to the program so that the shape by the material removal along the to be formed contour of the fitting body. The too forming contour was previously from an optical scanning of the pretreated tooth in which the dental fitting body to be used.

EP-A-0 455 853 also describes a process for Creation of dental prosthetic fittings known. Here the processing is done simultaneously by two tools mounted on different tool heads.

The problem arises when machining the workpiece, that the removal rate of the tools along the forming contour of the fitting body is usually not constant.

In some places on the contour there is a very strong one Material removal, especially if a fitting body with steep flanks or strong depressions shall be. In other places, however, the Material removal be very low, e.g. if a flat, smooth surface should be created.

Too high a removal rate can lead to overheating of the tool up to its destruction. It is very important to make sure that during maximum of the total machining of the workpiece Load on the tools is not exceeded.

For this purpose, it has been suggested at constant Rotation frequency of the rotating tool Monitor the power consumption of the rotary drive. This power consumption then represents a measure of the current load on the tool. Exceeds the Power consumption a certain maximum value, so the feed rate between the workpiece and Tool reduced so far that the power consumption falls below the maximum value again.

With such a procedure can in many cases satisfactory regulation can be achieved. Yet this regulation is often not sufficient to Performance peaks that lead to greatly increased wear and tear of the Tool can reliably prevent. Such power peaks can then in particular occur when rapid changes between a low Removal rate and a high removal rate occur. For example, this is often the case with Working out sharp-edged structures with steep Flanks the case, as is often the case with tooth crowns occur.

So there is the task of a process for Specify creation of medical passports at effectively avoid the stress peaks of the tools and where the fitting body in the shortest possible time can be manufactured.

This problem is solved by a method for Creation of medical, in particular dental fitting bodies, in which a workpiece is made to which the fitting body is created, using a tool is machined, whereby the tool and the Workpiece has a relative movement along a path execute and being the actual load of the Tool for regulating the speed of the Relative movement is used. According to the invention the expected load on the tool along the Path calculated and used to control the speed used.

By the expected removal rate of the tool Calculated in advance can be very difficult rapid load changes are recognized early and at Control of movement between workpiece and tool be taken into account. That way Power peaks effectively excluded from the outset. While for example for those parts of the web, at who can expect a high stock removal rate from a slow speed between in advance Tool and workpiece is selected, the movement in Regions with only minimal removal take place very quickly. This leads to a considerable saving in time Manufacture of the fitting body. Furthermore, the forces reduced between tool and workpiece.

This method can then be used in particular insert when the tool is essentially is cylindrically symmetrical and by means of a Rotary drive rotates around its axis of symmetry. The tool is essentially an advantageous one cylindrical grinding pin with a lateral surface and an end face.

There are two options in particular for that Determination of the current load on the tool. According to the first possibility, it is used as a measure of the actual load on the tool Rotation frequency of the tool at essentially constant power consumption of the rotary drive determined. According to the second option, is used as a measure of the actual load the power consumption of the Rotary drive at a given rotation frequency determined.

a) linerarer Vorschub zwischen dem Werkzeug und dem Werkstück entlang einer Vorschubrichtung, die im wesentlichen senkrecht zur Symmetrieachse des Werkzeuges ist;

b) Tiefenänderung des Werkzeuges im Werkstück im wesentlichen entlang der Symmetrieachse des Werkzeuges; und

c) eindimensionale Seitwärtsbewegung zwischen dem Werkzeug und dem Werkstück entlang eines vorgegebenen Weges in einer Ebene, die im wesentlichen senkrecht zur Symmetrieachse des Werkzeuges verläuft und verschieden von der Richtung des linearen Vorschubs ist.

The types of relative movement between the tool and the workpiece are often predetermined by the device with which the fitting body is created. The method according to the invention can be used particularly well if the relative movement between the tool and the workpiece comprises the following types of movement:

a) linear feed between the tool and the workpiece along a feed direction that is substantially perpendicular to the axis of symmetry of the tool;

b) change in depth of the tool in the workpiece substantially along the axis of symmetry of the tool; and

c) one-dimensional sideways movement between the tool and the workpiece along a predetermined path in a plane which is substantially perpendicular to the axis of symmetry of the tool and is different from the direction of the linear feed.

The one-dimensional sideways movement exists preferably in a pivoting of the tool an axis that is substantially parallel to Axis of symmetry of the tool is. But it is also conceivable a transverse displacement of the tool a direction that is substantially perpendicular to both Axis of symmetry of the tool as well as to the direction of the is linear feed.

To complicated structures from the workpiece To be able to work out, it can make sense if the Relative movement between the tool and the workpiece further rotation of the workpiece around an axis includes which is substantially parallel to the direction of the is linear feed.

The desired contour from the workpiece is advantageous worked out in such a way that the linear Gradually feed the entire machining in the in the same direction. The feed takes place sensibly in steps that are small compared to the mean diameter of the tool. The web will divided into sections between which no linear Feed occurs. The expected load is then for each section from the comparison of the path along this section and the path of each previous section. Everyone Movement section can be from the above Movement types b) and c), that means from one Depth change of the tool and a one-dimensional one Sideways movement, put it together. The calculation of the expected removal rate can point at at least one selected point of the Movement section take place.

If the tool is a cylindrical one Abrasive pencil, it is advantageous to calculate the the expected load in the following way: To determine a measure for the expected Load when the depth of the grinding pin changes Approximately that part of the workpiece Determines the end face on which material is removed. The speed of the change in depth of the tool Workpiece is then at maximum speed limited, which is determined by accessing a table in which for several values of the share of Face on which material is removed, the assigned maximum speed is stored.

The regulation of the one-dimensional sideways movement. To determine a Measure of the expected load at the one-dimensional sideways movement becomes the height that part of the outer surface of the grinding pin calculated on which material is removed. The Speed of one-dimensional sideways movement is then limited to a maximum speed that is determined by accessing a table in which for multiple values of the amount of that proportion of Lateral surface on which material is removed, the assigned maximum speed is stored.

Fig. 1

Eine Prinzipskizze zur Bearbeitung des Werkstücks,

Fig. 2

die Lage des Schleifstiftes im Werkstück in einer ersten Bearbeitungsphase,

Fig. 3

die Lage des Schleifstiftes im Werkstück in einer zweiten Bearbeitungsphase, sowie

Fig. 4

einen schematischen Plan zum Ablauf der Regelung.

Advantageous embodiments of the method according to the invention are explained with the aid of the drawing. Show it:

Fig. 1

A basic sketch for machining the workpiece,

Fig. 2

the position of the grinding pin in the workpiece in a first machining phase,

Fig. 3

the position of the grinding pin in the workpiece in a second machining phase, as well

Fig. 4

a schematic plan for the course of the scheme.

1 shows a workpiece 1 on a holder 2 assembled. This is in a not shown Workpiece spindle clamped and by means of Workpiece spindle in the axial direction along the Feed direction V slidable. Above the image plane a cylinder grinder, not shown, is arranged, which is stored in a tool spindle and by means of a rotary drive can be set in rotation. The The cylinder grinder rotates around an axis, the vertically on the image plane and thus also vertically stands on the feed direction V.

By means of a suitable drive device, the Cylinder grinder in the tool spindle along the Rotation axis of the tool, i.e. perpendicular to the Image plane, moved towards and away from the tool become. This corresponds to a change in depth of the Cylinder grinder in the workpiece along the Axis symmetry. In addition, the Tool spindle around an axis, not shown, in the Image plane can be pivoted. Here describes the Cylinder grinder an arcuate path relative to Workpiece. Some such tracks, depending on the current one The amount of feed of the workpiece along V, are in 1 with 4, 5 and 6.

To illustrate the sequence of movements at Machining the workpiece is assumed to be in the course a contour can be generated in workpiece 1 during machining should, as indicated by the contour lines 3. This contour is therefore an irregular one shaped depression in workpiece 1 in the image plane inside. For example, such a contour Occlusal surface of a tooth crown that is made from the workpiece to be manufactured.

At the beginning of the processing is the Workpiece spindle with the holder 2 and the one on it attached workpiece 1 in its initial position with respect to the feed direction V. The cylinder grinder is located in relation to the feed direction V am upper end of the workpiece 1. After a zero adjustment the tools, as described, for example, in EP-A-0 455 853 is described, the real begins Machining process. For this, the grinding pin is removed a suitable feed of the workpiece in direction V and a suitable pivoting of the tool spindle brought the position A. The rotating grinding pen now starts machining the workpiece by moved towards the workpiece along its axis of rotation until its end face touches the workpiece and with material removal begins.

As soon as the grinding pin in the desired amount Workpiece has penetrated, the tool spindle pivoted along the direction 4, being continuous or gradually change the depth of the Grinding pin in the workpiece. That way the first path section of the contour to be worked out generated.

Once editing along this section is completed, the workpiece 1 is a small one Amount shifted along the feed direction V. The The size of the feed cut depends in particular on the desired precision when working out the Contour. In any case, it is much smaller than the diameter of the grinding pin.

After executing this feed step, the Tool spindle along a parallel to direction 4 pivoted back web, being continuous the depth of the grinding pin in the workpiece is changed and so a second section of the contour to be generated is worked out. This sequence out Feed steps and then working out the Contour along a path section by swiveling the tool spindle and depth change of the tool is now continued until the entire contour is worked out. The feed is always in the same direction along the feed direction V.

Figures 2 and 3 illustrate the removal of the Workpiece material in different phases during the Machining the workpiece 1. The representation of the Figures 2 and 3 are in section from the side, wherein the viewing direction with respect to FIG. 1 from the left lies within the image plane. The situation in FIG. 2 corresponds approximately to the state at point B, the Situation of Fig. 3 roughly the state at point C. Both Fig. 2 and Fig. 3 are as are to be understood as a highly schematic representation in particular not to scale.

2, the grinding pin 7 has several Feed steps the position shown in the workpiece 1 reached. Here he has the area 8 of the desired Contour worked out of workpiece 1. After one further feed step of the workpiece 1 in the direction V the grinding pin 7 now works a further section the contour out of the workpiece 1. For this he is using the tool spindle pivots, causing a movement in corresponds to the image plane in or out of it, and its depth in the workpiece is changed, which one Movement of the grinding pin up or down corresponds to the axis of rotation 9.

The same applies analogously to FIG. 3. It is now a larger part 8 'of the desired contour in Workpiece 1 worked out. Here too follows every feed step in direction V the movement of the Tool into or out of the paper plane or up or down along the axis of rotation 9.

During the machining of the workpiece 1 different types of loads or load cases for the Distinguish grinding pin 7. The first load case is so-called front load case. This occurs when the grinding pin 7 along its axis of rotation in the Workpiece 1 is moved into it. A material removal takes place here only on the face of the grinding pin. There are different situations here. In the first situation, the entire face of the Part of the material removal. This is for Example if the case in Fig. 2 Grinding pin 7 down along its axis of rotation is moved. One can see a complete one here speak front load case. In the other situation only takes up part of the end face of the material removal part. This is the case, for example, if the Grinding pin 7 in Fig. 3 along its Direction of rotation is shifted down. Here 3 is only removed from the lower right End of the sharpening pencil.

A similar distinction can also be made for the Swiveling the grinding pencil into the plane of the paper or be hit out of it. For example in Fig. 2 the grinding pin far enough in the Swung in the paper plane, so there is a Material removal on a relatively large part of the Lateral surface. This part lies in FIG. 2 on the back side of the grinding pin and is through the special hatching indicated. So it's high jacket-side load. 3 takes place on the other hand, material removal only with a proportionate small proportion of the outer surface of the grinding pin 7, the is again indicated by the hatching.

It is therefore evident that in the course of processing of the workpiece very different loads of the Tool (grinding pin 7) can occur.

To prevent it from overloading the Tool occurs, there are now different variants conceivable. The first and simplest variant is the speed of the Relative movement between tool and workpiece on one limit low maximum value. With enough lower Choosing this speed leads to the fact that even in the worst case, no overloading of the Tool can be done. By doing so, one effectively overloads the tool prevent, however, the processing time of the Workpiece in an unacceptable manner.

A second variant, according to the prior art So far, the burden has been practiced of the tool to determine continuously and the Relative movement between tool and workpiece based on regulate the determined load. This will for example the frequency of rotation of the tool regulated that this remains largely constant; it will then the power consumption of the tool drive determined, for example by measuring the current at an electric tool drive. This Power consumption is an immediate measure of that current load on the tool. The regulation of Relative speed between tool and workpiece then takes place in such a way that the Relative speed between tool and workpiece is lowered and vice versa. With an ideal, such a regulation works without delay could the workpiece with a constant stock removal rate and constant load on the tool become.

This is sufficient, especially for rapid load changes Regulation of the relative speed alone is not enough. It is according to the present invention by a Predetermination of the expected removal rate or

Tool load added. That way the movement between tool and workpiece in those areas in which a high stock removal rate is expected to be very slow from the start and vice versa in areas where only one low stock removal rate is expected to be higher Relative speed between tool and workpiece to get voted.

The sequence of the method according to the invention is schematically illustrated in FIG. 4. The geometrical Data of the fitting body to be created are in one Computing and storage unit 10 stored. In case of Manufacture of a dental prosthetic fitting can this data, for example, on known Way from an optical 3D image of an area of Oral cavity can be obtained. From this geometric data calculates the computing and storage unit 10 on the one hand the path on which the machining tool and the Move the workpiece relative to each other and on the other hand for a number of points on this path the expected one Removal rate of the tool. Finally, the Computing and control unit 10 control signals therefrom passes them on to a control unit 11. The Control unit 11 regulates various electromotive, hydraulic or pneumatic Drives used to perform a relative movement are provided between the tool and the workpiece. In the Fig. 4, these drives are schematic to one Drive unit 12 summarized. In addition to the Control signals from the computing and control device 10 the control device 11 also receives signals by a drive control 13, with the help of electromotive rotary drive 14 of the Machining tool is regulated. The regulation is done in such a way that the rotational frequency of the processing tool remains largely constant. The control unit 11 is then fed signals the information about the power consumption of the Rotary drive 14 included. From the signals of the Computing and control unit 10 on the one hand and the Drive control 13 on the other hand determines the Control unit 11 the necessary manipulated variables for Drive unit 12, which are required to Relative movement between tool and workpiece the calculated path.

A method for calculating the expected Material removal rate in the computing and control device 10 is explained in more detail below.

The web is in the computing and control device 10 first divided into a number of sections, during which there is no linear feed of the workpiece along the feed direction. For each Section can now calculate the point by point Swivel position of the tool and the calculation of the Depth of the tool in the workpiece. In principle the path can thus be represented by a large number of triples of numbers, with the first numerical value each Tripels the track section, the second numerical value the Swivel position of the tool and the third numerical value indicates the depth of the tool in the workpiece. If that Workpiece additionally rotates around the feed axis carries out another numerical value for the Angle of rotation of the workpiece.

The calculation of the baby data need not be for the Entire web completely before the start of the grinding process respectively. It can also be carried out in sections be, for example, during the grinding of a Track section for the next track section.

• Für jeden Punkt der Bahn läßt sich zunächst berechnen, ob ein Materialabtrag mit der Stirnseite des Schleifstiftes erfolgt. Falls dies der Fall ist, kann weiterhin näherungsweise derjenige Anteil der Stirnfläche des Schleifstiftes berechnet werden, an dem ein Materialabtrag stattfindet. In die Rechen- und Steuereinheit 10 wurde zuvor eine Tabelle eingespeichert, in der für verschiedene Anteile der Stirnfläche, an denen ein Abtrag stattfindet, die jeweils maximal zulässige Geschwindigkeit für die Tiefenänderung des Schleifstiftes im Werkstück eingetragen ist. Diese Maximalgeschwindigkeit wurde zuvor für das jeweilige Werkstückmaterial empirisch im Labor ermittelt.
• Ebenfalls ermöglicht der abschnittsweise Vergleich der Bahndaten die Berechnung desjenigen Anteils der Mantelfläche, an dem ein Materialabtrag stattfindet. In der Rechen- und Steuereinheit 10 wurde zuvor eine weitere Tabelle eingetragen, in der für verschiedene Werte des Anteils der Mantelfläche die jeweils maximale zulässige Geschwindigkeit für die Schwenkbewegung des Werkzeuges relativ zum Werkstück eingetragen ist. Durch Vergleich mit dieser Tabelle kann so für jeden Punkt der Bahn die maximal zulässige Schwenkgeschwindigkeit ermittelt werden.

To explain the regulation of the relative movement between the tool and the workpiece, let us first assume that the machining of a certain number of path sections has already taken place. At this point in time, at least the path data of the last path section worked out and the path data of the next path section to be processed are stored in the computing and control unit 10. The computing and control unit 10 now compares point by point for each swivel position of the grinding pin the depth of the grinding pin in the workpiece on the last worked out and on the next to be worked out path. Two things can be identified by this comparison:

• For each point on the path, it can first be calculated whether there is material removal with the end face of the grinding pin. If this is the case, the portion of the end face of the grinding pin on which material is removed can also be approximately calculated. A table was previously stored in the computing and control unit 10, in which the maximum permissible speed for the change in depth of the grinding pin in the workpiece is entered for different portions of the end face on which ablation takes place. This maximum speed was previously determined empirically for the respective workpiece material in the laboratory.
• The section-by-section comparison of the web data also enables the calculation of that portion of the lateral surface on which material is removed. A further table was previously entered in the computing and control unit 10, in which the maximum permissible speed for the pivoting movement of the tool relative to the workpiece is entered for different values of the proportion of the lateral surface. By comparing this table, the maximum permissible swivel speed can be determined for each point on the path.

If the workpiece is additionally rotated around the Feed axis V is executed, the same applies analogously also for the maximum speed for the rotation of the Workpiece around this axis.

The computing and control device 10 now conducts signals to the control unit 11, which are suitable for the Drive for pivoting the tool and the To control the change in depth of the tool. If the Drive, for example, contains stepper motors the computing and control device 10 to the Control device 11 information on the at each Number of adjustment steps to be carried out by the Stepper motor and the chronological order of these Adjustment steps. The chronological order of the Adjustment steps are laid in particular by Relative motion speed fixed. It will be like this chosen that this speed is close, but below the calculated maximum permissible speed.

The control device 11 controls this Signals directly the drives for the Swiveling movement and the change in depth of the tool as well as the drive after the end of each rail section for the workpiece feed. It receives from the Control device 13 information about the current Load on the grinding pin. In optimal conditions, that is, with exact adjustment of the tools, one new and thus powerful grinding pen, more optimal Cooling etc. becomes the instantaneous load determined largely match the calculated load. The control device does not need in this case intervene. However, the grinding pin is worn and therefore less efficient than expected, or lie other non-optimal operating conditions, so the actual load on the grinding pin is higher than the calculated load. In this case, the Control device 11 regulating, in which it Relative speed between tool and workpiece lowers.

• Die Bewegungsgeschwindigkeit des Schleifstifts kann an Positionen, an denen nur ein geringer Materialabtrag erfolgt, erheblich gesteigert werden. Hierdurch ergibt sich eine kürzere Gesamtbearbeitungsdauer bei der Fertigung eines Werkstücks. Dies ist insbesondere dann von Bedeutung, wenn aus dem Werkstück ein zahnärztlicher Prothetikpaßkörper gefertigt werden soll, der unmittelbar in der Praxis des Zahnarztes im Mund des Patienten eingesetzt werden soll.
• Die Kräfte zwischen Werkstück und Schleifstift werden insbesondere an solchen Positionen, an denen viel Material abgetragen werden muß, durch die dort reduzierte Bewegungsgeschwindigkeit erheblich vermindert. Dies ist insbesondere dann von Bedeutung, wenn filigrane Formen mit geringer Materialstärke ausgearbeitet werden sollen. Bei übermäßiger Krafteinwirkung zwischen Schleifstift und Werkstück können solche Formen leicht abbrechen. Ebenso wird ein Abbrechen des Schleifstiftes verhindert.
• In jeder denkbaren Betriebssituation ist eine ausreichende Kühlung des Schleifstiftes gewährleistet. Bei der Erkennung einer starken Belastung des Schleifstiftes kann die Regelungseinrichtung 11 so eingestellt werden, daß unter Umständen sogar ein vollständiges Zurückziehen des Schleifstiftes aus dem Werkzeug erfolgt. Dies erlaubt eine schnelle Kühlung der belasteten Flächen und das Ausspülen von abgetragenen Partikeln aus Vertiefungen im Werkstück.
• Das Verfahren ist nicht nur bei Einsatz eines Schleifstiftes anwendbar, sondern ebensogut auch für andere Werkzeuge wie Fräser oder Schleif- und Trennscheiben.
• Schließlich ermöglicht das vorgeschlagene Verfahren eine selbsttätige Erkennung der Abnutzung des Schleifstiftes. Eine solche Erkennung kann über die Überwachung der Häufigkeit des Eingreifens der Regelung 11 aufgrund einer übermäßigen Belastung des Schleifstiftes erfolgen. Bei einem zu häufigen Eingreifen der Regelung über einen längeren Zeitraum kann der Benutzer durch eine geeignete Signaleinrichtung dazu aufgefordert werden, den Schleifstift zu wechseln.

The combination of a prediction of the expected load and a determination of the actual momentary load for the purpose of regulating the relative movement between tool and workpiece brings with it a number of advantages, some of which are mentioned here:

• The speed of movement of the grinding pin can be increased considerably at positions where only a small amount of material is removed. This results in a shorter total machining time when manufacturing a workpiece. This is particularly important if a dental prosthetic fitting is to be made from the workpiece and is to be used directly in the dentist's practice in the patient's mouth.
• The forces between the workpiece and the grinding pin are considerably reduced, in particular at positions where a lot of material has to be removed, by the reduced speed of movement there. This is particularly important when filigree shapes with low material thickness are to be worked out. Such forms can easily break off when excessive force is applied between the grinding pin and the workpiece. The grinding pin is also prevented from breaking off.
• Adequate cooling of the grinding pin is guaranteed in every conceivable operating situation. When a strong load on the grinding pin is detected, the control device 11 can be set in such a way that under certain circumstances there is even a complete withdrawal of the grinding pin from the tool. This allows the contaminated surfaces to be cooled quickly and rinsed particles to be rinsed out of depressions in the workpiece.
• The method can be used not only when using a grinding pin, but also for other tools such as milling cutters or grinding and cutting discs.
• Finally, the proposed method enables the wear of the grinding pin to be recognized automatically. Such a detection can take place by monitoring the frequency of intervention of the control 11 due to an excessive load on the grinding pin. If the control intervenes too often over a longer period of time, the user can be prompted by a suitable signaling device to change the grinding pin.

The control method according to the invention can often without apparatus change to existing devices for Creation of medical fitting bodies implemented become. Such a device is in any case anyway comprise a computing and control device that After suitable programming, the functionality of the Take over computing and control device 10 of FIG. 4 can. Likewise, in many existing ones Devices already have a control unit for detection of overload. Instead of a fixed maximum Relative speed between workpiece and tool this control unit is now a variable maximum Relative speed given by the respective Path point is dependent. So can easily and a very reliable at low cost Scheme can be achieved.

Reference list

1

workpiece

2nd

holder

3rd

contour to be created

4 - 6

Track sections

7

Grinding pin

8, 8 '

worked out contour

9

Axis of rotation

A, B, C

Edit points

V

Feed direction

Claims (13)

Process for creating medical, especially dental fitting bodies, in which a Workpiece (1) from which the fitting body is created, is removed by means of a tool (7), the tool (7) and the workpiece (1) being one Execute relative movement along a path and where the actual load on the tool (7) Regulation of the speed of the relative movement is used, characterized in that the to expected load on the tool (7) along the Path calculated and used to control the Relative speed is used. A method according to claim 1, characterized in that the tool (7) is essentially cylindrical symmetry is and by means of a rotary drive around his Axis of symmetry (9) rotates. A method according to claim 2, characterized in that as a measure of the actual load on the tool (7) whose rotation frequency at essentially constant power consumption of the rotary drive is determined. A method according to claim 2, characterized in that as a measure of the actual load on the tool (7) the power consumption of the rotary drive at im determined substantially constant rotation frequency becomes. Method according to one of claims 2 to 4, characterized in that the relative movement between the tool (7) and the workpiece (1) comprises the following types of movement: a) linear feed between tool (1) and workpiece (7) along a feed direction (V) which is substantially perpendicular to the axis of symmetry (9) of the tool; b) change in depth of the tool (7) in the workpiece (1) substantially along the axis of symmetry (9) of the tool (7); c) one-dimensional sideways movement between the tool (1) and the workpiece (7) along a predetermined path (5; 5; 6) in a plane which is substantially perpendicular to the axis of symmetry (9) of the tool (1). A method according to claim 5, characterized in that the one-dimensional sideways movement in one Swiveling the tool (7) about an axis which in substantially parallel to the axis of symmetry (9) of the Tool (7) is. A method according to claim 5 or 6, characterized characterized in that the relative movement between the Tool (7) and the workpiece (1) still one Rotation of the workpiece (1) comprises an axis which is substantially parallel to the feed direction (V). Method according to one of claims 5 to 7, characterized characterized in that the tool (7) in essential cylindrical grinding pin with a Shell surface and an end face is. A method according to claim 8, characterized in that the linear feed takes place in steps that are small compared to the diameter of the grinding pin, that the path is divided into sections between which there is no linear feed and that the expected load for each section is calculated from the comparison of the path along that section and the path along the previous section. A method according to claim 9, characterized in that to determine the expected load with a one-dimensional sideways movement the Height of the proportion of the lateral surface of the Grinding wheel is calculated on the one Material removal takes place. A method according to claim 10, characterized characterized that the speed of the one-dimensional sideways movement on a Maximum speed is limited to below Access to a table is determined in which for several values of the amount of that portion of the Lateral surface on which material is removed, the assigned maximum speed is saved is. Method according to one of claims 9 to 11, characterized in that to determine the expected load with a change in depth of the Approximately grinding pin in the workpiece that proportion of the end face is determined which material is removed. A method according to claim 12, characterized characterized that the speed of the Depth change of the tool in the workpiece a maximum speed is limited which is determined by accessing a table in the for multiple values of the share of Face on which material is removed, the assigned maximum speed is saved is.

Images